mlx5r_umr_dm..._update_pgsz(9)

💅 mlx5r_umr_dmabuf_update_pgsz(9)

okay so first thing, bestie — this is a page from the Kernel API Manual, section 9 (the kernel-functions girlypop section ✨). The function we're stanning today is mlx5r_umr_dmabuf_update_pgsz, and the header up top shortens it to mlx5r_umr_dm..._update_pgsz(9) because even manpage headers get tired. Anyway. Let's get into it 🎀

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✨ NAME ✨

mlx5r_umr_dmabuf_update_pgsz — safely update a DMABUF MR's page size and its entries accordingly 🦋

🌸 SYNOPSIS 🌸

int mlx5r_umr_dmabuf_update_pgsz (struct mlx5_ib_mr *mr , u32 xlt_flags
, u32 pdn , unsigned int page_shift );

🎀 ARGUMENTS 🎀

• mr — the memory region you're updating, like the main character of this whole operation 👑
• xlt_flags — the translation table update flags. flags! for the translation table! updating! iykyk 💅
• pdn — the protection domain number
• page_shift — the new (optimized) page shift to use. yes bestie, optimized ✨

🔥 DESCRIPTION 🔥

So here's the vibe: this function updates the page size and the mkey translation entries for a DMABUF MR, and it does it in a safe, multi-step process — literally so it never exposes partially updated mappings. no cap, that's the whole point 🫶

The update happens in 5 steps:

1. Make the first X entries non-present, while X is calculated to be minimal according to a large page shift that can be used to cover the MR length
2. Update the page size to the large supported page size
3. Load the remaining N-X entries according to the (optimized) page_shift
4. Update the page size according to the (optimized) page_shift
5. Load the first X entries with the correct translations

the way this is sequenced?? iconic. it ensures that at no point is the MR accessible with a partially updated translation table — which maintains correctness and prevents access to stale or inconsistent mappings. that's the correctness girlie behavior we love to see 😭💖

Returns 0 on success or a negative error code on failure. (so like, check your return value, bestie. always. 🙈)

ngl the "never half-updated" thing is the entire personality of this function — don't skip a step, don't reorder them, and definitely don't let anything read the table mid-glow-up 💀

⭐ SEE ALSO ⭐

• Kernel file ./drivers/infiniband/hw/mlx5/umr.c
• mlx5r_umr_revoke_mr(9)

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and that's the page!! 🧚 this one lives under ./drivers/infiniband/hw/mlx5 in the Kernel API Manual, dated October 2026 — so yeah, it's giving future-kernel energy, slay 💜✨